The value of dynamic contrast-enhanced MRI in the detection of recurrent prostate cancer after external beam radiotherapy: correlation with transrectal ultrasound and pathological findings.

PURPOSE: To assess the effectiveness of dynamic contrast-enhanced (DCE) T1- and T2-weighted magnetic resonance imaging (MRI) during the follow-up of patients with prostate cancer after undergoing external beam radiotherapy (EBRT) and to compare these imaging findings to pathological and transrectal ultrasound (TRUS) findings.
MATERIALS AND METHODS: In this retrospective study, the MRI findings of 20 patients who had prostate cancer and were treated with EBRT were evaluated to detect tumor recurrence. The MRI findings were compared to those that had been obtained by TRUS and pathological analysis.
RESULTS: The sensitivity and specificity of TRUS in the detection of tumor recurrence in patients who had undergone EBRT were 53.3% and 60%, respectively. In the same group of patients, the sensitivity and specificity of T2-weighted MRI were 86% and 100%, respectively. Strikingly, the sensitivity and specificity of DCE T1-weighted MRI in the diagnosis of recurrent prostate cancer were 93% and 100%, respectively. The accuracy of the DCE T1-weighted images in the detection of recurrence was significantly higher in comparison to that obtained using T2-weighted images.
CONCLUSION: During the follow-up of these patients, TRUS without the use of any other imaging or biochemical modality is not a sufficient method for the detection of prostate cancer recurrence. DCE T1-weighted MRI increases the sensitivity of MRI alone for the detection of recurrence during the follow-up of prostate cancer patients who have been treated with EBRT. Thus, DCE T1-weighted MRI must be used as part of the routine MRI analysis to check for tumor recurrence in patients with prostate cancer.